A slide of potato cells was viewed using a light microscope - Edexcel - GCSE Biology Combined Science - Question 2 - 2020 - Paper 1

The correct answer here is D: cell wall, chloroplast, large vacuole. Plant cells contain a cell wall that provides structure and support, chloroplasts for photosynthesis, and a large vacuole for storage and maintaining turgor pressure.

Using the data from Figure 5, for potato 2 at 5 weeks, the mean length of starch grains is 50 μm, and for potato 3 at 10 weeks, it is 30 μm. The formula for percentage difference is:

$ext{Percentage Difference} = \frac{|50 - 30|}{\frac{50 + 30}{2}} \times 100$

Calculating this:

$= \frac{20}{40} \times 100 = 50\%$

Therefore, the percentage difference is 50%.

1. Temperature of the storage environment, as it can affect starch grain growth and conversion.
2. Light exposure, to ensure that the effect of darkness is consistent across all tested potatoes.

Potatoes need glucose for energy and respiration. Glucose is a vital source of energy that is used in cellular processes.

Starch is broken down into glucose through a process called hydrolysis, which is facilitated by enzymes such as amylase. The enzyme binds to the starch molecule at the active site and breaks the bonds between glucose monomers in starch, producing simpler sugars like glucose. This process occurs in the digestive system and within plant cells.